Method of making electric heaters



E. N. LIGHTFOOT METHOD OF MAKING ELECTRIC HEATERS Original Filed Feb. 5,1921 Patented Aug. 30, 1927.

EDWIN N. LIGHTFOOT, OF MILWAUKEE,

PATENT OFF/ICE.

WISCONSIN, ASSIGNOR TO THE CUTLER- HAMMER MFG. 00., OF MILWAUKEE,WISCONSIN, A CORPORATION OF WISCONSIN.

METHOD OF MAKING ELECTRIC HEATERS.

Application filed February 5, 1921, Serial No. 442,882. Renewed February2, 1927.

This invention relates to the method of Enaking electric heaters andmachine there- More particularly the invention relates to the method ofand means for insulating the resistor of an electric heater from theenclosing jacket thereof.

One of the objects of the invention is to provide an improved method ofinsulating the resistor of an electric heater.

Another object is to provide an improved method of insulating theresistor of an electric heater from the enclosing jacket thereof withinsulation in one form and subsequently changing the physicalcharacteristics of the insulation.

Other-objects and advantages will hereinafter appear.

The views of the drawings are:

Fig. 1 is a side elevation of a filling machine;

Fig. 2 is an enlarged vertical section through the filling head shown inFig. 1;

Fig. 3 is an enlarged horizontal section on line 33 of Fig. 1;

Fig. l is a transverse section on line M of Fig. 3; and

Fig. 5 is a top plan of the filling machine.

The method in general consists of introducing between the resistor andthe tubular jacket of an electric heater insulation in one form, such asa plastic mass and thereafter changing the form into a hard compact massby drying'the insulation and thereafter compressing and compacting theinsulation in the jacket and around and about the resistor.

The material used for the plastic may be any suitable electricalinsulating material. such as -magnesium oxide. preferablyin powderedform mixed with sufiicient kaolin. china clay. ball clay or any suchmaterial as will when mixed with aliquid such as water give'a' plasticmass that will fiow under pressure.

The machine. by means of which a tubular acket of an electric heater maybe filled with insulation, may consist of a filling head 1, to which atubular jacket may be attached for filling, and a container 2 for theinsulating material, connected to the filling head by means of a tube 3.

The filling head 1 may be provided with a central chamber 4 to which oneend of a tubular jacket 5 may be connected by means of a joint orbushing 6 and pliable packing material 7 for exam le felt. The packing 7when compresse by screwing the bushing 6 into the filling head, gripsthe jacket 5 thereby holding it firmly in position and also forms a.tight joint between the jacket and filling head to prevent egress ofinsulation when the jacket is being filled.

The container 2 comprises a cylinder or barrel 8 with an internallytravelling head or disc 9 provided with a threaded aperture into which athreaded rod 10 may be screwed to move the head from one end of thebarrel to the other. The threaded rod 10 may be rotated by a handle 11or other suitable means.

The barrel 8 may be provided with an internal slot 12 to preventrotation of the disc 9.

Before the heater jacket 5 is attached to the filling head, a plugterminal 13 with a resistor 14 connected thereto and extending upwardlyWithin the jacket is inserted in the lower end of the heater jacket. Thefree end of the resistor is preferably connected to some means such as adrum fastened to a ratchet 15 for the purpose of holding the resistortaut.

For the purpose of centering the resistor within the tubular jacket andto insure against imperfect fillin of the jacket, a filling tube 16surrounting the resistor is inserted through the filling head 1 andextended to the bottom portion of the heater jacket.

' to the bottom of the heater jacket.

lVhen the plastic insulation reaches the bottom of the jacket 5 it thenflows up through the filling tube surrounding the resistor. The fillingtube may be Withdrawn gradually as the plastic flows up around theresistor. Consequently when the operation is completed and the fillingtube entirely withdrawn the heater jacket is completely filled and theresistor completely surrounded by and embedded in the plastic.

The filling tube 16 may be provided with a set of radially extendinglugs or fingers 18 to keep the tube centered with respect to the heaterjacket.

After the heater jacket is completely filled in the manner described aplug terminal is inserted in and securely fastened to the other end ofthe jacket.

The plastic insulation may then be dried into a hard compactmass bypassing current through the resistor.

After the insulation has been thoroughly dried the heater jacket may becontracted crosswise by swaging or other suitable means to thereby breakup the insulation into fine particles or powder, and compress andcompact the powdered insulation around and about the resistor.

The heater jacket may contracted by a swaging machine such as disclosedin Patent 1,359,400, dated November 16, 1920.

While but one embodiment has been shown and described, various otherembodiments and adaptations may be made of the invention containedherein.

The invention claimed is:

1. The method of insulating the resistor of an electric heater from theenclosing j acket thereof, which comprises surrounding the resistor withinsulation in one form and subsequently changing the physicalcharacteristics thereof.

2. The method of insulating the resistor of an electric heater from theenclosing jacket thereof, which comprises surrounding the resistor withinsulation in one form and subsequently altering the physicalcharacteristics thereof and compressing and compacting the same in thejacket and around and about the resistor.

3. The method of insulating the resistor of an electric heater from theenclosing jacket thereof which comprises surrounding the resistor withinsulation in plastic form and subsequently altering the physicalcharacteristics thereof.

4. The method of insulating the resistor of an electric heater from theenclosing jacket thereof which comprises surrounding the resistor withinsulation in plastic form and subsequently reducing the insulation to ahard compact mass.

6. The method of insulating the resistor of an electric heater from theenclosing jacket thereof which comprises surrounding the resistor withinsulation in plastic form and subsequently drying the insulation andreducing it to powder formation.

7. The method of insulating the resistor of an electric heater from theenclosing j ack et thereof which comprises surrounding the resistor withinsulation in plastic form and subsequently drying the insulation andcompressing and compacting thesame in the jacket and around and aboutthe resistor.

8. The method of insulating the resistor of an electric heater from theenclosing casing thereof which comprises centering the resistor withinthe heater casing and surrounding the resistor with insulation in oneform and subsequently changing the physical characteristics thereof.

9. The method of insulating the resistor of an electric heater from theenclosing casresistor within the heater casing, surrounding the resistorwith insulation in one form and subsequently altering the physicalcharacteristics thereof and compressing and compacting the same in thejacket and around the resistor.

10. The method of insulating the resistor of an electric heater from theenclosing jacket thereof, which comprises positioning the resistorwithin the jacket, introducing into the jacket an emulsion of theinsulation and a liquid, and then subjecting the insulation to treatmentto remove the liquid therefrom and to bring the particles of insulationinto intimate contactto minimize the voids between the particles.

11. The method of insulating the helical resistor of an electric heaterfrom the enclosing jacket thereof, which comprises positioning theresistor within the jacket, introducing the insulation into said jacketwith a liquid medium, and then subjecting the insulation to treatment toremove the liquid therefrom and compact the mass thereof.

12. The method of insulating the resistor of an electric heater from theenclosing casing thereof, which comprises filling said casing withinsulation in plastic form to embed said resistor, positively centeringsaid resistor, during the filling operation, heating said insulation toform a hard compact mass, and

iI1g thereof which comprises centering the IQU hen disintegrating saidmass while main- Leining said resistor centered with respect to thecasing.

13. The method of insulating the helical resistor 021: an electricheater from the enclosing casing thereof, which comprises surroundingthe resistor with insulation in plastic term and subsequently alteringthe physical characteristics thereof by the application of heat, andcompressing and com- 110 pacting the same in the casing and around andabout the resistor v In witness whereof I have hereunto subscribed myname.

EDWIN N. LIGHTFOOT.

